Phosphors

ABSTRACT

Compounds containing an anionic scaffold structure, dopants and cations, in which
     a. the anionic scaffold structure features coordination tetrahedra GL 4 , where G stands for silicon, which may be partly replaced by C, Ge, B, Al or In, and L stands for N and O, with the proviso that N makes up at least 60 atom % of L;   b. the cations are alkaline earth metals, with the proviso that strontium and barium together make up less than 75 atom % of the cations;   c. dopant present trivalent cerium or a mixture of trivalent cerium and divalent europium;   d. charge compensation of the cerium doping is accomplished i) through corresponding replacement of alkaline earth metal cations by alkali metal cations, and/or ii) by a corresponding increase in the nitrogen content, and/or iii) by a corresponding reduction in the cations; and to processes for preparing, and to their use as conversion phosphors.

The present invention relates to novel compounds, to a process for thepreparation thereof and to the use thereof as conversion phosphors. Thepresent invention also relates to an emission-converting materialcomprising at least the conversion phosphor according to the inventionand to the use thereof in light sources, in particular so-called pc-LEDs(phosphor converted light emitting devices). The present inventionfurthermore relates to light sources, in particular pc-LEDs, andlighting units which contain a primary light source and theemission-converting material according to the invention.

For more than 100 years, inorganic phosphors have been developed inorder to adapt the spectra of emissive display screens, X-ray amplifiersand radiation or light sources in such a way that they meet therequirements of the respective area of application in as optimal amanner as possible and at the same time consume as little energy aspossible. The type of excitation, i.e. the nature of the primaryradiation source and the requisite emission spectrum, is of crucialimportance here for the choice of host lattice and the activators.

In particular for fluorescent light sources for general lighting, i.e.for low-pressure discharge lamps and light-emitting diodes, novelphosphors are constantly being developed in order further to increasethe energy efficiency, colour reproduction and stability.

There are in principle three different approaches to obtainingwhite-emitting inorganic LEDs (light emitting diodes) by additive colourmixing:

-   (1) The so-called RGB LEDs (red+green+blue LEDs), in which white    light is generated by mixing the light from three different    light-emitting diodes which emit in the red, green and blue spectral    region.-   (2) The UV LED+RGB phosphor systems, in which a semiconductor    emitting in the UV region (primary light source) emits the light to    the environment, in which three different phosphors (conversion    phosphors) are stimulated to emit in the red, green and blue    spectral region.-   (3) So-called complementary systems, in which an emitting    semiconductor (primary light source) emits, for example, blue light,    which stimulates one or more phosphors (conversion phosphors) to    emit light, for example in the yellow region. By mixing the blue and    yellow light, white light, for example, is then produced.

Binary complementary systems have the advantage that they are capable ofproducing white light with only one primary light source and—in thesimplest case—with only one conversion phosphor. The best-known of thesesystems consists of an indium aluminium nitride chip as primary lightsource, which emits light in the blue spectral region, and acerium-doped yttrium aluminium garnet (YAG:Ce) as conversion phosphor,which is stimulated in the blue region and emits light in the yellowspectral region. However, improvements in the colour rendering index andthe stability of the colour temperature are desirable.

On use of a blue-emitting semiconductor as primary light source, theseso-called binary complementary systems thus require a yellow conversionphosphor or green- and red-emitting conversion phosphors in order toreproduce white light. If, as an alternative, the primary light sourceused is a semiconductor which emits in the violet spectral region or inthe near-UV spectrum, either an RGB phosphor mixture or a dichromaticmixture of two complementary light-emitting conversion phosphors must beused in order to obtain white light.

On use of a system having a primary light source in the violet or UVregion and two complementary conversion phosphors, light-emitting diodeshaving a particularly high lumen equivalent can be provided. A furtheradvantage of a dichromatic phosphor mixture is the lower spectralinteraction and the associated higher package gain.

In particular, inorganic fluorescent powders which can be excited in theblue and/or UV region of the spectrum are therefore gaining ever-greaterimportance today as conversion phosphors for light sources, inparticular for pc-LEDs.

In the meantime, many conversion phosphors have been disclosed, forexample alkaline-earth metal orthosilicates, thiogallates, garnets andnitrides, each of which are doped with Ce³⁺ or Eu²⁺.

However, there is a constant demand for novel conversion phosphors whichcan be excited in the blue or UV region and then emit light in thevisible region, in particular in the yellow spectral region.

A first embodiment of the present invention is therefore a compoundcontaining an anionic skeleton structure, dopants and cations, where

-   -   a. the anionic skeleton structure is characterised by        coordination tetrahedra GL₄-, where G stands for silicon, which        may be partly replaced by C, Ge, B, Al or In, and L stands for N        and O, with the proviso that N makes up at least 60 atom-% of L,    -   b. the cations are selected from the alkaline-earth metals, with        the proviso that strontium and barium together make up less than        75 atom-% of the cations,    -   c. the dopant present is trivalent cerium or a mixture of        trivalent cerium and divalent europium,    -   d. the charge compensation of the cerium doping takes place i)        via corresponding replacement of alkaline-earth metal cations by        alkali-metal cations and/or ii) via a corresponding increase in        the nitrogen content and/or iii) via a corresponding reduction        in the alkaline-earth metal cations.

The term anionic skeleton structure here relates to the structure motifin the composition, in which G is generally present in coordinationtetrahedra. These tetrahedra may be linked to one another via one ormore common L atoms and thus form extended anionic partial structuralelements in the solid. Corresponding structure motifs are usuallydetected using crystallographic methods for structure determination oralso via spectroscopic methods and are well known to the person skilledin the art, in particular from silicate chemistry.

In general, the determination of the structure of inorganic solidmaterials is carried out on the basis of a combination ofcrystallographic data, optionally spectroscopic data and of informationon the elemental composition, which, in the case of quantitativereaction, can either arise from the composition of the startingmaterials or alternatively is determined by methods of elementalanalysis. Corresponding methods are well established in chemicalanalysis and can therefore be presumed to be known to the person skilledin the art. Amount data in atom-% relate to numerical ratios of atoms ofcertain chemical elements to larger groups which can usually occupy thesame lattice sites in crystal structure, such as, for example, nitrogenand oxygen as L.

The compounds according to the invention can usually be excited in theblue spectral region, preferably at 450 nm, and usually emit in theyellow spectral region. The compounds according to the inventionotherwise have properties comparable to the 2-5-8 nitrides, where thesemake significantly lower requirements of the preparation processes withrespect to oxygen content and phase purity or have lower sensitivity tomoisture.

In the context of this application, emission in the red region or redlight denotes light whose intensity maximum is at a wavelength between600 nm and 670 nm; correspondingly, green or emission in the greenregion denotes light whose maximum is at a wavelength between 508 nm and550 nm, and yellow or emission in the yellow region denotes light whosemaximum is at a wavelength between 551 nm and 599 nm.

In a preferred variant of the invention, the alkaline-earth metalcations are strontium, magnesium, calcium and/or barium, where calciumand magnesium together make up 25 atom-% or more of the alkaline-earthmetal cations and in the same or a further alternative embodimentcalcium and magnesium together make up from 30 atom-% to 80 atom-% ofthe alkaline-earth metal cations.

In a further alternative or the same variant of the invention, magnesiumis present as one of the alkaline-earth metal cations.

In the same or another variant of the invention, G stands for more than80 atom-% of silicon or for more than 90 atom-% of silicon. It may alsobe preferred in accordance with the invention for G to be formed bysilicon. Alternatively, it may be preferred for silicon to have beenpartly replaced by C or Ge.

In particular, the compound according to the invention can be a compoundof the formula Ia,

A_(2-0.5y-x+1.5z)M_(0.5x)Ce_(0.5x)G₅N_(8-y+z)O_(y)  (Ia)

where

A stands for one or more elements selected from Ca, Sr, Ba, Mg,

M stands for one or more elements selected from Li, Na, K,

G stands for Si, which may be partly replaced by C, Ge, B, Al or In,

x stands for a value from the range from 0.005 to 1 and

y stands for a value from the range from 0.01 to 3 and

z stands for a value from the range from 0 to 3.

Alternatively, the compound according to the invention can be a compoundof the formula Ib,

A_(2-0.5y-0.75x+1.5z)Ce_(0.5x)G₅N_(8-y+z)O_(y)  (Ib)

where

A stands for one or more elements selected from Ca, Sr, Ba, Mg,

M stands for one or more elements selected from Li, Na, K,

G stands for Si, which may be partly replaced by C, Ge, B, Al or In,

x stands for a value from the range from 0.005 to 1 and

y stands for a value from the range from 0.01 to 3 and

z stands for a value from the range from 0 to 3.

Again alternatively, the compound according to the invention can be acompound of the formula Ic,

A_(2-0.5y+1.5z)Ce_(0.5x)G₅N_(8+0.5x-y+z)O_(y)  (Ic)

where

A stands for one or more elements selected from Ca, Sr, Ba, Mg,

M stands for one or more elements selected from Li, Na, K,

G stands for Si, which may be partly replaced by C, Ge, B, Al or In,

x stands for a value from the range from 0.005 to 1 and

y stands for a value from the range from 0.01 to 3 and

z stands for a value from the range from 0 to 3.

In the said compounds of the formulae Ia, Ib and Ic, it may be desiredfor x to stand for a value from the range from 0.01 to 0.8,alternatively from the range 0.02 to 0.7 and furthermore alternativelyfrom the range 0.05 to 0.6.

At the same time or alternatively, it may be desired for y to stand fora value from the range from 0.1 to 2.5, preferably from the range 0.2 to2 and especially preferably from the range 0.22 to 1.8.

At the same time or alternatively, it may be desired for z to stand forthe value 0, or a value from the range from 0.1 to 2.5, preferably fromthe range 0.2 to 2 and especially preferably from the range 0.22 to 1.8.

It has proven essential in accordance with the invention for cerium tobe present as dopant. In various variants of the invention, cerium canbe the only dopant or can be used in combination with further dopants.Dopants which can be used in this case are conventional divalent ortrivalent rare-earth ions or sub-group metal ions. In one variant, it ispreferred for europium to be present in the dopant alongside cerium. Inthis variant, it has been shown that the stability is increased if thecations contain a proportion of barium, so this combination may be apreferred combination.

The compound here may be in the form of a pure substance or a mixture.The present invention therefore furthermore relates to a mixturecomprising at least one compound, as defined above, and at least onefurther silicon- and oxygen-containing compound.

In mixtures of this type, the compound is usually present in aproportion by weight from the range 30-95% by weight, preferably fromthe range 50-90% by weight and especially preferably from the range60-88% by weight.

In preferred embodiments of the invention, the at least one silicon- andoxygen-containing compound comprises x-ray-amorphous or glass-likephases which are distinguished by a high silicon and oxygen content, butmay also contain metals, in particular alkaline-earth metals, such asstrontium. It may in turn be preferred for these phases to fully orpartly surround the particles of the compound.

It is preferred in accordance with the invention for the at least onefurther silicon- and oxygen-containing compound to be a reactionby-product of the preparation of the compound and for this to notadversely affect the application-relevant optical properties of thecompound.

The invention therefore furthermore relates to a mixture comprising acompound of the formula I which is obtainable by a process in which, ina step a), suitable starting materials selected from binary nitrides,halides and oxides or corresponding reactive forms thereto are mixed,and, in a step b), the mixture is thermally treated under reductiveconditions.

The invention furthermore relates to the corresponding process for thepreparation of the compounds and to the use according to the inventionof the compounds as phosphor or conversion phosphor, in particular forthe partial or complete conversion of the blue or near-UV emission froma primary light source, preferably a luminescent diode or a laser.

The compounds according to the invention are also referred to below asphosphors.

Compounds according to the invention give rise to good LED qualitieseven when employed in small amounts. The LED quality is described herevia conventional parameters, such as, for example, the colour renderingindex, the correlated colour temperature, lumen equivalent or absolutelumen, or the colour point in CIE x and CIE y coordinates.

The colour rendering index or CRI is a dimensionless lighting quantity,familiar to the person skilled in the art, which compares the colourreproduction faithfulness of an artificial light source with that ofsunlight or filament light sources (the latter two have a CRI of 100).

The CCT or correlated colour temperature is a lighting quantity,familiar to the person skilled in the art, with the unit kelvin. Thehigher the numerical value, the colder the white light from anartificial radiation source appears to the observer. The CCT follows theconcept of the black body radiator, whose colour temperature follows aPlanck curve in the CIE diagram.

The lumen equivalent is a lighting quantity, familiar to the personskilled in the art, with the unit lm/W which describes the magnitude ofthe photometric luminous flux in lumens of a light source at a certainradiometric radiation power with the unit watt. The higher the lumenequivalent, the more efficient a light source.

The lumen is a photometric lighting quantity, familiar to the personskilled in the art, which describes the luminous flux of a light source,which is a measure of the total visible radiation emitted by a radiationsource. The greater the luminous flux, the brighter the light sourceappears to the observer.

CIE x and CIE y stand for the coordinates in the standard CIE colourchart (here standard observer 1931), familiar to the person skilled inthe art, by means of which the colour of a light source is described.

All the quantities mentioned above are calculated from emission spectraof the light source by methods familiar to the person skilled in theart.

In addition, the excitability of the phosphors according to theinvention extends over a broad range, which extends from about 410 nm to530 nm, preferably 430 nm to about 500 nm.

Furthermore advantageous in the case of the phosphors according to theinvention is the stability to moisture and water vapour, which may enterthe LED package via diffusion processes from the environment and maythus reach the surface of the phosphor, and the stability to acidicmedia, which may arise as by-products in the curing of the binder in theLED package or as additives in the LED package. Phosphors which arepreferred in accordance with the invention have stabilities which arehigher than the nitridic phosphors which are usual to date.

The phosphors according to the invention can be prepared analogously topreviously known processes for the preparation of undoped or Eu-dopednitrides and oxynitrides, where the person skilled in the art ispresented with no difficulties in replacing the respective Eu source bya corresponding cerium source. Known processes for the preparation ofM₂Si₅N₈:Eu are, for example:

(2−x)M+xEu+5Si(NH₂)→M_(2-x)Eu_(x)Si₅N₈+5H₂  (1)

-   (Schnick et al., Journal of Physics and Chemistry of Solids (2000),    61(12), 2001-2006)

(2−x)M₃N₂+3xEuN+5Si₃N₄→3M_(2-x)Eu_(x)Si₅N₈+0.5xN₂  (2)

-   (Hintzen et al., Journal of Alloys and Compounds (2006), 417(1-2),    273-279)

(2−x)MO+1.666Si₃N₄+0.5xEu₂O₃+(2+0.5x)C+1.5N₂→M_(2-x)Eu_(x)Si₅N₈+(2+0.5x)CO  (3)

-   (Piao et al., Applied Physics Letters 2006, 88, 161908)

2Si₃N₄+2(2−x)MCO₃ +x/2Eu₂O₃→M_(2-x)Eu_(x)Si₅N₈+M₂SiO₄+CO₂  (4)

-   (Xie et al., Chemistry of Materials, 2006, 18, 5578)

(2−x)M+xEu+5SiCl₄+28NH₃→M_(2-x)Eu_(x)Si₅N₈+20NH₄Cl+2H₂  (5)

-   (Jansen et al., WO 2010/029184 A1).    -   Silicooxynitrides are accessible, for example, by stoichiometric        mixing of SiO₂, M₃N₂, Si₃N₄ and EuN and subsequent calcination        at temperatures of about 1600° C. (for example in accordance        with WO 2011/091839).    -   Of the above processes for the preparation of siliconitrides,        process (2) is particularly suitable since the corresponding        starting materials are commercially available, no secondary        phases are formed in the synthesis, and the efficiency of the        materials obtained is high.

In a process according to the invention for the preparation of phosphorsaccording to the invention, suitable starting materials selected frombinary nitrides, halides and oxides or corresponding reactive formsthereto are therefore mixed in a step a), and the mixture is, in a stepb), thermally treated under non-oxidising conditions.

This process is frequently followed by a second calcination step, whichincreases the efficiency of the material a little further. In thissecond calcination step, it may be helpful to add alkaline-earth metalnitride. In a variant of the invention, pre-sintered oxynitride toalkaline-earth metal nitride is employed in the ratio 2:1 to 20:1, in analternative variant in the ratio 4:1 to 9:1. This post-calcinationenables the emission maximum of the target compound to be shifted, sothat the specific addition of alkaline-earth metal nitride can beutilised in order to set a desired emission maximum exactly.

The reaction in step b) and also the optional post-calcination areusually carried out at a temperature above 800° C., preferably at atemperature above 1200° C. and especially preferably in the range 1400°C.-1800° C. Usual durations for these steps are 2 to 14 h, alternatively4 to 12 h and again alternatively 6 to 10 h.

The non-oxidising conditions here are established, for example, usinginert gases or carbon monoxide, forming gas or hydrogen or vacuum oroxygen-deficiency atmosphere, preferably in a stream of nitrogen,preferably in a stream of N₂/H₂ and especially preferably in a stream ofN₂/H₂/NH₃.

The calcination can be carried out, for example, by introducing theresultant mixtures into a high-temperature oven, for example in a boronnitride vessel. In a preferred embodiment, the high-temperature oven isa tubular furnace which contains a molybdenum foil tray.

After the calcination, the compounds obtained are, in a variant of theinvention, treated with acid in order to wash out unreactedalkaline-earth metal nitride. The acid used is preferably hydrochloricacid. The powder obtained here is, for example, suspended in 0.5 molarto 2 molar hydrochloric acid, more preferably 1 molar hydrochloric acid,for 0.5 to 3 h, more preferably 0.5 to 1.5 h, subsequently filtered offand dried at a temperature in the range from 80 to 150° C.

In a further alternative embodiment of the invention, the calcinationand workup, which can be carried out as described above by acidtreatment, are again followed by a further calcination step. This ispreferably carried out in a temperature range from 200 to 400° C.,particularly preferably from 250 to 350° C. This further calcinationstep is preferably carried out under a reducing atmosphere. The durationof this calcination step is usually between 15 minutes and 10 h,preferably between 30 minutes and 2 h.

In still a further embodiment, the compounds obtained by one of theabove-mentioned processes according to the invention can be coated.Suitable for this purpose are all coating methods as are known to theperson skilled in the art from the prior art and are used for phosphors.Suitable materials for the coating are, in particular, metal oxides andnitrides, in particular alkaline-earth metal oxides, such as Al₂O₃, andalkaline-earth metal nitrides, such as AlN, and SiO₂. The coating can becarried out here, for example, by fluidised-bed methods. Furthersuitable coating methods are known from JP 04-304290, WO 91/10715, WO99/27033, US 2007/0298250, WO 2009/065480 and WO 2010/075908.

The present invention furthermore relates to a light source having atleast one primary light source which comprises at least one compoundaccording to the invention. The emission maximum of the primary lightsource here is usually in the range 410 nm to 530 nm, preferably 430 nmto about 500 nm. A range between 440 and 480 nm is especially preferred,where the primary radiation is converted partly or fully intolonger-wave radiation by the phosphors according to the invention.

In a preferred embodiment of the light source according to theinvention, the primary light source is a luminescent indium aluminiumgallium nitride, in particular of the formula In_(i)Ga_(j)Al_(k)N, where0≦i, 0≦j, 0≦k, and i+j+k=1.

Possible forms of light sources of this type are known to the personskilled in the art. These can be light-emitting LED chips of variousstructure.

In a further preferred embodiment of the light source according to theinvention, the primary light source is a luminescent arrangement basedon ZnO, TCO (transparent conducting oxide), ZnSe or SiC or anarrangement based on an organic light-emitting layer (OLED).

In a further preferred embodiment of the light source according to theinvention, the primary light source is a source which exhibitselectroluminescence and/or photoluminescence. The primary light sourcemay furthermore also be a plasma or discharge source.

Corresponding light sources according to the invention are also known aslight-emitting diodes or LEDs.

The phosphors according to the invention can be employed individually oras a mixture with the following phosphors, which are familiar to theperson skilled in the art. Corresponding phosphors which are inprinciple suitable for mixtures are, for example:

Ba₂SiO₄:Eu²⁺, BaSi₂O₅:Pb²⁺, Ba_(x)Sr_(1-x)F₂:Eu²⁺, BaSrMgSi₂O₇:Eu²⁺,BaTiP₂O₇, (Ba,Ti)₂P₂O₇:Ti, Ba₃WO₆:U, BaY₂F₈:Er³⁺,Yb⁺, Be₂SiO₄:Mn²⁺,Bi₄Ge₃O₁₂, CaAl₂O₄:Ce³⁺, CaLa₄O₇:Ce³⁺, CaAl₂O₄:Eu²⁺, CaAl₂O₄:Mn²⁺,CaAl₄O₇:Pb²⁺, Mn²⁺, CaAl₂O₄:Tb³⁺, Ca₃Al₂Si₃O₁₂:Ce³⁺, Ca₃Al₂Si₃O₁₂:Ce³⁺,Ca₃Al₂Si₃O₁₂:Eu²⁺, Ca₂B₅O₉Br:Eu²⁺, Ca₂B₅O₉Cl:Eu²⁺, Ca₂B₅O₉Cl:Pb²⁺,CaB₂O₄:Mn²⁺, Ca₂B₂O₅:Mn²⁺, CaB₂O₄:Pb²⁺, CaB₂P₂O₉:Eu²⁺, Ca₅B₂SiO₁₀:Eu³⁺,Ca_(0.5)Ba_(0.5)Al₁₂O₁₉:Ce³⁺,Mn²⁺, Ca₂Ba₃(PO₄)₃Cl:Eu²⁺, CaBr₂:Eu²⁺ inSiO₂, CaCl₂:Eu²⁺ in SiO₂, CaCl₂:Eu²⁺,Mn²⁺ in SiO₂, CaF₂:Ce³⁺,CaF₂:Ce³⁺,Mn²⁺, CaF₂:Ce³⁺,Tb³⁺, CaF₂:Eu²⁺, CaF₂:Mn²⁺, CaF₂:U,CaGa₂O₄:Mn²⁺, CaGa₄O₇:Mn²⁺, CaGa₂S₄:Ce³⁺, CaGa₂S₄:Eu²⁺, CaGa₂S₄:Mn²⁺,CaGa₂S₄:Pb²⁺, CaGeO₃:Mn²⁺, CaI₂:Eu²⁺ in SiO₂, CaI₂:Eu²⁺, Mn²⁺ in SiO₂,CaLaBO₄:Eu³⁺, CaLaB₃O₇:Ce³⁺,Mn²⁺, Ca₂La₂BO_(6.5):Pb²⁺, Ca₂MgSi₂O₇,Ca₂MgSi₂O₇:Ce³⁺, CaMgSi₂O₆:Eu²⁺, Ca₃MgSi₂O₈:Eu²⁺, Ca₂MgSi₂O₇:Eu²⁺,CaMgSi₂O₆:Eu²⁺,Mn²⁺, Ca₂MgSi₂O₇:Eu²⁺, Mn²⁺, CaMoO₄, CaMoO₄:Eu³⁺,CaO:Bi³⁺, CaO:Cd²⁺, CaO:Cu⁺, CaO:Eu³⁺, CaO:Eu³⁺, Na⁺, CaO:Mn²⁺,CaO:Pb²⁺, CaO:Sb³⁺, CaO:Sm³⁺, CaO:Tb³⁺, CaO:Tl, CaO:Zn²⁺, Ca₂P₂O₇:Ce³⁺,α-Ca₃(PO₄)₂:Ce³⁺, β-Ca₃(PO₄)₂:Ce³⁺, Ca₅(PO₄)₃Cl:Eu²⁺, Ca₅(PO₄)₃Cl:Mn²⁺,Ca₅(PO₄)₃Cl:Sb³⁺, Ca₅(PO₄)₃Cl:Sn²⁺, β-Ca₃(PO₄)₂:Eu²⁺,Mn²⁺,Ca₅(PO₄)₃F:Mn²⁺, Ca_(s)(PO₄)₃F:Sb³⁺, Ca_(s)(PO₄)₃F:Sn²⁺,α-Ca₃(PO₄)₂:Eu²⁺, β-Ca₃(PO₄)₂:Eu²⁺, Ca₂P₂O₇:Eu²⁺, Ca₂P₂O₇:Eu²⁺, Mn²⁺,CaP₂O₆:Mn²⁺, α-Ca₃(PO₄)₂:Pb²⁺, α-Ca₃(PO₄)₂:Sn²⁺, β-Ca₃(PO₄)₂:Sn²⁺,β-Ca₂P₂O₇:Sn,Mn, α-Ca₃(PO₄)₂:Tr, CaS:Bi³⁺, CaS:Bi³⁺,Na, CaS:Ce³⁺,CaS:Eu²⁺, CaS:Cu⁺, Na⁺, CaS:La³⁺, CaS:Mn²⁺, CaSO₄:Bi, CaSO₄:Ce³⁺,CaSO₄:Ce³⁺, Mn²⁺, CaSO₄:Eu²⁺, CaSO₄:Eu²⁺, Mn²⁺, CaSO₄:Pb²⁺, CaS:Pb²⁺,CaS:Pb²⁺, Cl, CaS:Pb²⁺, Mn²⁺, CaS:Pr³⁺, Pb²⁺, Cl, CaS:Sb³⁺, CaS:Sb³⁺,Na, CaS:Sm³⁺, CaS:Sn²⁺, CaS:Sn²⁺, F, CaS:Tb³⁺, GaS:Tb³⁺, Cl, GaS:Y³⁺,GaS:Yb²⁺, GaS:Yb²⁺, Cl, CaSiO₃:Ce³⁺, Ca₃SiO₄Cl₂:Eu²⁺, Ca₃SiO₄Cl₂:Pb²⁺,CaSiO₃:Eu²⁺, CaSiO₃:Mn²⁺,Pb, CaSiO₃:Pb²⁺, CaSiO₃:Pb²⁺,Mn²⁺, CaSiO₃:Ti⁴⁺,CaSr₂(PO₄)₂:Bi³⁺, β-(Ca,Sr)₃(PO₄)₂:Sn²⁺Mn²⁺, CaTi_(0.9)Al_(0.1)O₃:Bi³⁺,CaTiO₃:Eu³⁺, CaTiO₃:Pr³⁺, Ca₅(VO₄)₃Cl, CaWO₄, CaWO₄:Pb²⁺, CaWO₄:W,Ca₃WO₆:U, CaYAlO₄:Eu³⁺, CaYBO₄:Bi³⁺, CaYBO₄:Eu³⁺,CaYB_(0.8)O_(3.7):Eu³⁺, CaY₂ZrO₆:Eu³⁺, (Ca,Zn,Mg)₃(PO₄)₂:Sn, CeF₃,(Ce,Mg)BaAl₁₁O₁₈:Ce, (Ce,Mg)SrAl₁₁O₁₈:Ce, CeMgAl₁₁O₁₉:Ce:Tb,Cd₂B₆O₁₁:Mn²⁺, CdS:Ag⁺,Cr, CdS:In, CdS:In, CdS:In,Te, CdS:Te, CdWO₄,CsF, CsI, CsI:Na⁺, CsI:Tl, (ErCl₃)_(0.25)(BaCl₂)_(0.75), GaN:Zn,Gd₃Ga₅O₁₂:Cr³⁺, Gd₃Ga₅O₁₂:Cr,Ce, GdNbO₄:Bi³⁺, Gd₂O₂S:Eu³⁺, Gd₂O₂Pr³⁺,Gd₂O₂S:Pr,Ce,F, Gd₂O₂S:Tb³⁺, Gd₂SiO₅:Ce³⁺, KAl₁₁O₁₇:Tl⁺, KGa₁₁O₁₇:Mn²⁺,K₂La₂Ti₃O₁₀:Eu, KMgF₃:Eu²⁺, KMgF₃:Mn²⁺, K₂SiF₆:Mn⁴⁺, LaAl₃B₄O₁₂:Eu³⁺,LaAlB₂O₆:Eu³⁺, LaAlO₃:Eu³⁺, LaAlO₃:Sm³⁺, LaAsO₄:Eu³⁺, LaBr₃:Ce³⁺,LaBO₃:Eu³⁺, (La,Ce,Tb) PO₄:Ce:Tb, LaCl₃:Ce³⁺, La₂O₃:Bi³⁺, LaOBr:Tb³⁺,LaOBr:Tm³⁺, LaOCl:Bi³⁺, LaOCl:Eu³⁺, LaOF:Eu³⁺, La₂O₃:Eu³⁺, La₂O₃:Pr³⁺,La₂O₂S:Tb³⁺, LaPO₄:Ce³⁺, LaPO₄:Eu³⁺, LaSiO₃Cl:Ce³⁺, LaSiO₃Cl:Ce³⁺,Tb³⁺,LaVO₄:Eu³⁺, La₂W₃O₁₂:Eu³⁺, LiAlF₄:Mn²⁺, LiAl₅O₈:Fe³⁺, LiAlO₂:Fe³⁺,LiAlO₂:Mn²⁺, LiAl₅O₈:Mn²⁺, Li₂CaP₂O₇:Ce³⁺,Mn²⁺, LiCeBa₄Si₄O₁₄:Mn²⁺,LiCeSrBa₃Si₄O₁₄:Mn²⁺, LiInO₂:Eu³⁺, LiInO₂:Sm³⁺, LiLaO₂:Eu³⁺,LuAlO₃:Ce³⁺, (Lu,Gd)₂Si0₅:Ce³⁺, Lu₂SiO₅:Ce³⁺, Lu₂Si₂O₇:Ce³⁺,LuTaO₄:Nb⁵⁺, Lu_(1-x)Y_(x)AlO₃:Ce³⁺, MgAl₂O₄:Mn²⁺, MgSrAl₁₀O₁₇:Ce,MgB₂O₄:Mn²⁺, MgBa₂(PO₄)₂:Sn²⁺, MgBa₂(PO₄)₂:U, MgBaP₂O₇:Eu²⁺,MgBaP₂O₇:Eu²⁺, Mn²⁺, MgBa₃Si₂O₈:Eu²⁺, MgBa(SO₄)₂:Eu²⁺,Mg₃Ca₃(PO₄)₄:Eu²⁺, MgCaP₂O₇:Mn²⁺, Mg₂Ca(SO₄)₃:Eu²⁺,Mg₂Ca(SO₄)₃:Eu²⁺,Mn², MgCeAnO₁₉:Tb³⁺, Mg₄(F)GeO₆:Mn²⁺,Mg₄(F)(Ge,Sn)O₆:Mn²⁺, MgF₂:Mn²⁺, MgGa₂O₄:Mn²⁺, Mg₈Ge₂O₁₁F₂:Mn⁴⁺,MgS:Eu²⁺, MgSiO₃:Mn²⁺, Mg₂SiO₄:Mn²⁺, Mg₃SiO₃F₄:Ti⁴⁺, MgSO₄:Eu²⁺,MgSO₄:Pb²⁺, MgSrBa₂Si₂O₇:Eu²⁺, MgSrP₂O₇:Eu²⁺, MgSr₅(PO₄)₄:Sn²⁺,MgSr₃Si₂O₈:Eu²⁺, Mn²⁺, Mg₂Sr(SO₄)₃:Eu²⁺, Mg₂TiO₄:Mn⁴⁺, MgWO₄,MgYBO₄:Eu³⁺, Na₃Ce(PO₄)₂:Tb³⁺, NaI:Tl,Na_(1.23)K_(O.42)Eu_(0.12)TiSi₄O₁₁:Eu³⁺,Na_(1.23)K_(0.42)Eu_(0.12)TiSi₅O₁₃.xH₂O:Eu³⁺,Na_(1.29)K_(0.46)Er_(0.08)TiSi₄O₁₁:Eu³⁺, Na₂Mg₃Al₂Si₂O₁₀:Tb,Na(Mg_(2-x)Mn_(x))LiSi₄O₁₀F₂:Mn, NaYF₄:Er³⁺, Yb³⁺, NaYO₂:Eu³⁺,P46(70%)+P47 (30%), SrAl₁₂O₁₉:Ce³⁺, Mn²⁺, SrAl₂O₄:Eu²⁺, SrAl₄O₇:Eu³⁺,SrAl₁₂O₁₉:Eu²⁺, SrAl₂S₄:Eu²⁺, Sr₂B₅O₉Cl:Eu²⁺, SrB₄O₇:Eu²⁺(F, Cl, Br),SrB₄O₇:Pb²⁺, SrB₄O₇:Pb²⁺, Mn²⁺, SrB₈O₁₃:Sm²⁺,Sr_(x)Ba_(y)Cl_(z)Al₂O_(4-z/2): Mn²⁺, Ce³⁺, SrBaSiO₄:Eu²⁺,Sr(Cl,Br,I)₂:Eu²⁺ in SiO₂, SrCl₂:Eu²⁺ in SiO₂, Sr₅Cl(PO₄)₃:Eu,Sr_(w)F_(x)B₄O_(6.5):Eu²⁺, Sr_(w)F_(x)B_(y)O_(z):Eu²⁺,Sm²⁺, SrF₂:Eu²⁺,SrGa₁₂O₁₉:Mn²⁺, SrGa₂S₄:Ce³⁺, SrGa₂S₄:Eu²⁺, SrGa₂S₄:Pb²⁺, SrIn₂O₄:Pr³⁺,Al³⁺, (Sr,Mg)₃(PO₄)₂:Sn, SrMgSi₂O₆:Eu²⁺, Sr₂MgSi₂O₇:Eu²⁺,Sr₃MgSi₂O₈:Eu²⁺, SrMoO₄:U, SrO.3B₂O₃:Eu²⁺, Cl, β-SrO.3B₂O₃:Pb²⁺,β-SrO.3B₂O₃:Pb²⁺, Mn²⁺, α-SrO.3B₂O₃:Sm²⁺, Sr₆P₅BO₂₀:Eu,Sr₅(PO₄)₃Cl:Eu²⁺, Sr₅(PO₄)₃Cl:Eu²⁺,Pr³⁺, Sr₅(PO₄)₃Cl:Mn²⁺,Sr₅(PO₄)₃Cl:Sb³⁺, Sr₂P₂O₇:Eu²⁺, β-Sr₃(PO₄)₂:Eu²⁺, Sr₅(PO₄)₃F:Mn²⁺,Sr₅(PO₄)₃F:Sb³⁺, Sr₅(PO₄)₃F:Sb³⁺,Mn²⁺, Sr₅(PO₄)₃F:Sn²⁺, Sr₂P₂O₇:Sn²⁺,β-Sr₃(PO₄)₂:Sn²⁺, β-Sr₃(PO₄)₂:Sn²⁺,Mn²⁺(Al), SrS:Ce³⁺, SrS:Eu²⁺,SrS:Mn²⁺, SrS:Cu⁺,Na, SrSO₄:Bi, SrSO₄:Ce³⁺, SrSO₄:Eu²⁺, SrSO₄:Eu²⁺,Mn²⁺, Sr₅Si₄O₁₀Cl₆:Eu²⁺, Sr₂SiO₄:Eu²⁺, SrTiO₃:Pr³⁺, SrTiO₃:Pr³⁺,Al³⁺,Sr₃WO₆:U, SrY₂O₃:Eu³⁺, ThO₂:Eu³⁺, ThO₂:Pr³⁺, ThO₂:Tb³⁺,YAl₃B₄O₁₂:Bi^(3+,) YAl₃B₄O₁₂:Ce³⁺, YAl₃B₄O₁₂:Ce³⁺,Mn,YAl₃B₄O₁₂:Ce³⁺,Tb³⁺, YAl₃B₄O₁₂:Eu³⁺, YAl₃B₄O₁₂:Eu³⁺,Cr³⁺,YAl₃B₄O₁₂:Th⁴⁺,Ce³⁺,Mn²⁺, YAlO₃:Ce³⁺, Y₃Al₅O₁₂:Ce³⁺, Y₃A50O₁₂:Cr³⁺,YAlO₃:Eu³⁺, Y₃Al₅O₁₂:Eu³⁺, Y₄Al₂O₉:Eu³⁺, Y₃Al₅O₁₂:Mn^(4+,) YAlO₃:Sm³⁺,YAlO₃:Tb³⁺, Y₃Al₅O₁₂:Tb³⁺, YAsO₄:Eu³⁺, YBO₃:Ce³⁺, YBO₃:Eu³⁺,YF₃:Er³⁺,Yb³⁺, YF₃:Mn²⁺, YF₃:Mn²⁺,Th⁴⁺, YF₃:Tm³⁺,Yb³⁺, (Y,Gd)BO₃:Eu,(Y,Gd)BO₃:Tb, (Y,Gd)₂O₃:Eu³⁺, Y_(1.34)Gd_(0.60)O₃(Eu, Pr), Y₂O₃:Bi³⁺,YOBr:Eu³⁺, Y₂O₃:Ce, Y₂O₃:Er³⁺, Y₂O₃:Eu³⁺(YOE), Y₂O₃:Ce³⁺,Tb³⁺,YOCl:Ce³⁺, YOCl:Eu³⁺, YOF:Eu³⁺, YOF:Tb³⁺, Y₂O₃:Ho³⁺, Y₂O₂S:Eu³⁺,Y₂O₂S:Pr³⁺, Y₂O₂S:Tb³⁺, Y₂O₃:Tb³⁺, YPO₄:Ce³⁺, YPO₄:Ce³⁺,Tb³⁺, YPO₄:Eu³⁺,YPO₄:Mn²⁺,Th⁴⁺, YPO₄:V⁵⁺, Y(P,V)O₄:Eu, Y₂SiO₅:Ce³⁺, YTaO₄, YTaO₄:Nb⁵⁺,YVO₄:Dy³⁺, YVO₄:Eu³⁺, ZnAl₂O₄:Mn²⁺, ZnB₂O₄:Mn²⁺, ZnBa₂S₃:Mn²⁺,(Zn,Be)₂SiO₄:Mn²⁺, Zn_(0.4)Cd_(0.6)S:Ag, Zn_(0.6)Cd_(0.4)S:Ag,(Zn,Cd)S:Ag, Cl, (Zn,Cd)S:Cu, ZnF₂:Mn²⁺, ZnGa₂O₄, ZnGa₂O₄:Mn²⁺,ZnGa₂S₄:Mn²⁺, Zn₂GeO₄:Mn²⁺, (Zn,Mg)F₂:Mn²⁺, ZnMg₂(PO₄)₂:Mn²⁺,(Zn,Mg)₃(PO₄)₂:Mn²⁺, ZnO:Al³⁺,Ga³⁺, ZnO:Bi³⁺, ZnO:Ga³⁺, ZnO:Ga,ZnO—CdO:Ga, ZnO:S, ZnO:Se, ZnO:Zn, ZnS:Ag⁺,Cl⁻, ZnS:Ag,Cu,Cl, ZnS:Ag,Ni,ZnS:Au,In, ZnS—CdS (25-75), ZnS—CdS (50-50), ZnS—CdS (75-25),ZnS—CdS:Ag,Br,Ni, ZnS—CdS:Ag⁺, Cl, ZnS—CdS:Cu,Br, ZnS—CdS:Cu,I, ZnS:Cl⁻,ZnS:Eu²⁺, ZnS:Cu, ZnS:Cu+,Al³⁺, ZnS:Cu⁺,Cl⁻, ZnS:Cu,Sn, ZnS:Eu²⁺,ZnS:Mn²⁺, ZnS:Mn,Cu, ZnS:Mn²⁺,Te²⁺, ZnS:P, ZnS:P³⁻,Cl⁻, ZnS:Pb²⁺,ZnS:Pb²⁺,Cl⁻, ZnS:Pb,Cu, Zn₃(PO₄)₂:Mn²⁺, Zn₂SiO₄:Mn²⁺,Zn₂SiO₄:Mn²⁺,As⁵⁺, Zn₂SiO₄:Mn,Sb₂O₂, Zn₂SiO₄:Mn²⁺,P, Zn₂SiO₄:Ti⁴⁺,ZnS:Sn²⁺, ZnS:Sn,Ag, ZnS:Sn²⁺,Li, ZnS:Te,Mn, ZnS—ZnTe:Mn²⁺, ZnSe:Cu⁺,Cl, ZnWO₄

Furthermore, the compound according to the invention exhibits, inparticular, advantages in the mixture with further phosphors of adifferent fluorescence colour or on use in LEDs together with suchphosphors.

It has been found here that, in particular on combination of thecompounds according to the invention with red-emitting phosphors, theoptimisation of lighting parameters for white LEDs is achievedparticularly well.

Correspondingly, it is preferred in an embodiment according to theinvention for the light source to comprise a red-emitting phosphor inaddition to the phosphor according to the invention.

Corresponding phosphors are known to the person skilled in the art orcan be selected by the person skilled in the art from the list givenabove. Suitable red-emitting phosphors here are frequently nitrides,sialones or sulfides. Examples are: 2-5-8 nitrides, such as (Ca,Sr,Ba)₂Si₅N₈:Eu, (Ca,Sr)₂Si₅N₈:Eu, (Ca,Sr)AlSiN₃:Eu, (Ca,Sr)S:Eu,(Ca,Sr)(S,Se):Eu, (Sr,Ba,Ca)Ga₂S₄:Eu, and also oxynitridic compounds.

An advantage of the mixtures of oxynitrides compared with mixtures ofdifferent classes of substance are more homogeneous properties; thechemical stability, the morphology, the temperature behaviour, etc., ofthe phosphors are virtually identical. This facilitates stable lightproperties of the phosphor-converted LED and a homogeneous mixture ofthe phosphor components, reducing the binning expense in LEDconstruction.

Suitable oxynitrides are, in particular, the europium-dopedsilicooxynitrides. Corresponding preferred silicooxynitrides to beemployed substantially correspond in their composition to the compoundsaccording to the invention, where the dopant used is europium instead ofcerium.

In a variant, the red-emitting oxynitrides are those of the formula

A_(2-0.5y-x+1.5z)Eu_(x)Si₅N_(8-y+z)O_(y)

where A stands for one or more elements selected from Ca, Sr, Ba, and xstands for a value from the range from 0.005 to 1 and y stands for avalue from the range from 0.01 to 3 and z stands for a value from therange from 0 to 3. The preparation and use of corresponding compoundsare described in WO 2011/091839. Particular preference is given here tothe use of phosphors of the formula [Ca,Sr]_(2-0.5y-x+1.5z)Eu_(x)Si₅N_(8-y+z)O_(y).

In a further preferred embodiment of the invention, red-emittingcompounds of the formula

A_(2-c+1.5z)Eu_(c)Si₅N_(8-2/3x+z)O_(x)

are employed, where the indices used have the following meanings: Astands for one or more elements selected from Ca, Sr, Ba; 0.01≦c≦0.2;0<x≦1; 0≦z≦3.0 and a+b+c≦2+1.5z. Particular preference is given here tothe use of phosphors of the formula [Ca,Sr]_(2-c+1.5z)Eu_(c)Si₅N_(8-2/3x+z)O_(x). Corresponding compounds andpreparation processes are described in the earlier patent applicationwith the application file reference EP12005188.3. According to this, thecompounds can be obtained by a process in which a mixture of aeuropium-doped alkaline-earth metal siliconitride or europium-dopedalkaline-earth metal silicooxynitride and an alkaline-earth metalnitride is prepared, where the alkaline-earth metal of theeuropium-doped alkaline-earth metal siliconitride or silicooxynitrideand of the alkaline-earth metal nitride may be identical or different,and the mixture is calcined under non-oxidising conditions. Theeuropium-doped alkaline-earth metal siliconitride or silicooxynitrideemployed in the above-mentioned process is preferably a compound of thefollowing general formula EA_(d)Eu_(c)E_(e)N_(f)O_(x), in which thefollowing applies to the symbols and indices used: EA is at least onealkaline-earth metal, in particular selected from the group consistingof Ca, Sr and Ba; E is at least one element from the fourth main group,in particular Si; 0.80≦d≦1.995; 0.005≦c≦0.2; 4.0≦e≦6.00; 5.00≦f≦8.70;0≦x≦3.00; where the following relationship furthermore applies to theindices: 2d+2c+4e=3f+2x. The europium-doped alkaline-earth metalsiliconitride or silicooxynitride used in step (a) can be prepared byany process known from the prior art, as described, for example, in WO2011/091839. However, it is particularly preferred for theeuropium-doped alkaline-earth metal siliconitride or silicooxynitride tobe prepared by a step (a′) of calcination of a mixture comprising aeuropium source, a silicon source and an alkaline-earth metal nitrideunder non-oxidising conditions. This step (a′) precedes step (a) of theabove-mentioned process. The europium source employed can be anyconceivable europium compound with which a europium-doped alkaline-earthmetal siliconitride or silicooxynitride can be prepared. The europiumsource employed in the process according to the invention is preferablyeuropium oxide (in particular Eu₂O₃) and/or europium nitride (EuN), inparticular Eu₂O₃. The silicon source employed can be any conceivablesilicon compound with which a europium-doped alkaline-earth metalsiliconitride or silicooxynitride can be prepared. The silicon sourceemployed in the process according to the invention is preferably siliconnitride and optionally silicon oxide. If a pure nitride is to beprepared, the silicon source is preferably silicon nitride. If thepreparation of an oxynitride is desired, the silicon source employed isalso silicon dioxide besides silicon nitride. An alkaline-earth metalnitride is taken to mean a compound of the formula M₃N₂, in which M ison each occurrence, independently of one another, an alkaline-earthmetal ion, in particular selected from the group consisting of calcium,strontium and barium. In other words, the alkaline-earth metal nitrideis preferably selected from the group consisting of calcium nitride(Ca₃N₂), strontium nitride (Sr₃N₂), barium nitride (Ba₃N₂) and mixturesthereof. The compounds employed in step (a′) for the preparation of theeuropium-doped alkaline-earth metal siliconitride or silicooxynitrideare preferably employed in a ratio to one another such that the numberof atoms of the alkaline-earth metal, of silicon, of europium, ofnitrogen and, where present, of oxygen corresponds to the desired ratioin the alkaline-earth metal siliconitride or silicooxynitride of theabove-mentioned formula (I), (Ia), (Ib) or (II). In particular, astoichiometric ratio is used, but a slight excess of the alkaline-earthmetal nitride is also possible. The weight ratio of the europium-dopedalkaline-earth metal siliconitride or silicooxynitride to thealkaline-earth metal nitride in step (a) of the process according to theinvention is preferably in the range from 2:1 to 20:1 and morepreferably in the range from 4:1 to 9:1. The process here is carried outunder non-oxidising conditions, i.e. under substantially or completelyoxygen-free conditions, in particular under reducing conditions.

In a variant of the invention, it is in turn preferred for the phosphorsto be arranged on the primary light source in such a way that thered-emitting phosphor is essentially hit by light from the primary lightsource, while the yellow emitting phosphor is essentially hit by lightwhich has already passed through the red-emitting phosphor or has beenscattered thereby. This can be achieved by installing the red-emittingphosphor between the primary light source and the yellow-emittingphosphor.

The phosphors or phosphor combinations according to the invention caneither be dispersed in a resin (for example epoxy or silicone resin) or,in the case of suitable size ratios, arranged directly on the primarylight source or alternatively arranged remote therefrom, depending onthe application (the latter arrangement also includes “remote phosphortechnology”). The advantages of remote phosphor technology are known tothe person skilled in the art and are revealed, for example, by thefollowing publication: Japanese Journ. of Appl. Phys. Vol. 44, No. 21(2005). L649-L651.

In a further embodiment, it is preferred for the optical couplingbetween the phosphor and the primary light source to be achieved by alight-conducting arrangement. This makes it possible for the primarylight source to be installed at a central location and to be opticallycoupled to the phosphor by means of light-conducting devices, such as,for example, optical fibres. In this way, it is possible to achievelamps adapted to the lighting wishes which merely consist of one orvarious phosphors, which can be arranged to form a light screen, and anoptical waveguide, which is coupled to the primary light source. In thisway, it is possible to place a strong primary light source at a locationwhich is favourable for electrical installation and to install lampscomprising phosphors which are coupled to the optical waveguides at anydesired locations without further electrical cabling, but instead onlyby laying optical waveguides.

The invention furthermore relates to a lighting unit, in particular forthe backlighting of display devices, characterised in that it comprisesat least one light source according to the invention, and to a displaydevice, in particular liquid-crystal display device (LC display), withbacklighting, characterised in that it comprises at least one lightingunit according to the invention.

The particle size of the phosphors according to the invention on use inLEDs is usually between 50 nm and 30 μm, preferably between 1 μm and 20μm.

For use in LEDs, the phosphors can also be converted into any desiredouter shapes, such as spherical particles, platelets and structuredmaterials and ceramics. These shapes are in accordance with theinvention summarised under the term “shaped bodies”. The shaped body ispreferably a “phosphor body”. The present invention thus furthermorerelates to a shaped body comprising the phosphors according to theinvention. The production and use of corresponding shaped bodies arefamiliar to the person skilled in the art from numerous publications.

All variants of the invention described here can be combined with oneanother so long as the respective embodiments are not mutuallyexclusive. In particular, it is an obvious operation, on the basis ofthe teaching of this specification, as part of routine optimisation,precisely to combine various variants described here in order to obtaina specific particularly preferred embodiment. The following examples areintended to illustrate the present invention and show, in particular,the result of such illustrative combinations of the invention variantsdescribed. However, they should in no way be regarded as limiting, butinstead are intended to stimulate generalisation. All compounds orcomponents which can be used in the preparations are either known andcommercially available or can be synthesised by known methods. Thetemperatures indicated in the examples are always in ° C. It furthermoregoes without saying that, both in the description and also in theexamples, the amounts of the components added in the compositions alwaysadd up to a total of 100%. Percent data should always be regarded in thegiven connection.

EXAMPLES Example 1 Preparation of Various Compositions of Compounds ofthe Formula I According to the Invention Example 1 Synthesis ofMg_(1.0)Ca_(0.2)Ba_(0.72)Ce_(0.04)Na_(0.04)Si₅N_(7.67)O_(0.5)

In a glove box, 0.67 mmol of lithium nitride Li₃N, 2.00 mmol of ceriumnitride CeN, 79.17 mmol of silicon nitride Si₃N₄, 16.67 mmol ofmagnesium nitride Mg₃N₂, 3.33 mmol of calcium nitride Ca₃N₂, 12 mmol ofBa₃N₂ and 12.50 mmol of silicon dioxide SiO₂ are mixed and subsequentlyhomogenised by mortaring in an agate mortar. The mixture obtained inthis way is transferred into a boron nitride calcination dish andtransferred into a high-temperature oven under inert conditions. Thecalcination of the material is carried out at 1600° C. for 8 h withsupply of an N₂/H₂ gas mixture. The calcined sample is subsequentlymortared, sieved using a nylon sieve <36 m and characterised bycrystallography and spectroscopy.

The powder diagram of the product is shown in FIG. 1. The resultantproduct exhibits the fluorescence spectrum in accordance with FIG. 2 andthe excitation spectrum in accordance with FIG. 3.

Example 1b

The following compounds are prepared analogously:

Product Starting materialsMg_(0.3)Ca_(0.62)Ba_(1.0)Ce_(0.04)Li_(0.04)Si₅N_(7.67)O_(0.5) Mg₃N₂,Ca₃N₂, Ba₃N₂, CeN, Li₃N, Si₃N₄, SiO₂ Mg_(1.12)Ca_(0.4)Ba_(0.40)Ce_(0.04)Na_(0.04)Si₅N_(7.67)O_(0.5) Mg₃N₂, Ca₃N₂, Ba₃N₂, CeN,NaNO₃, Si₃N₄, SiO₂ Mg_(0.8)Ca_(0.4)Ba_(0.45)Ce_(0.05)Na_(0.05)Si₅N_(7.5)O_(0.5) Mg₃N₂, Ca₃N₂, Ba₃N₂, CeN,NaNO₃, Si₃N₄, SiO₂ Mg_(0.8)Ca_(0.4) Ba_(0.475)Ce_(0.05)Si₅N_(7.5)O_(0.5)Mg₃N₂, Ca₃N₂, Ba₃N₂, CeN, Si₃N₄, SiO₂ Mg_(0.79)Ca_(0.39)Ba_(0.465)Eu_(0.03)Ce_(0.05)Si₅N_(7.5)O_(0.5) Mg₃N₂, Ca₃N₂, Ba₃N₂, (cf.the fluorescence spectrum in FIG. 4) CeN, Si₃N₄, SiO₂, EuNMg_(0.19)Ca_(0.39) Ba_(1.065)Eu_(0.03)Ce_(0.05)Si₅N_(7.5)O_(0.5) Mg₃N₂,Ca₃N₂, Ba₃N₂, CeN, Si₃N₄, SiO₂, EuNMg_(0.97)Sr_(0.7)Ce_(0.04)Na_(0.04)Si₅N_(7.78)O_(0.22) Mg₃N₂, Sr₃N₂,CeN, Si₃N₄, SiO₂, NaNO₃Ca_(0.59)Ba_(1.33)Ce_(0.04)Na_(0.04)Si_(3.8)Ge_(1.2)N_(7.67)O_(0.5)Ba₃N₂, Ca₃N₂, CeN, Si₃N₄, Ge₃N₄, SiO₂, NaNO₃Ca_(0.29)Mg_(0.30)Ba_(1.33)Ce_(0.04)Na_(0.04)Si_(3.8)Ge_(1.2)N_(7.67)O_(0.5)Ba₃N₂, Ca₃N₂, Mg₃N₂, CeN, Si₃N₄, Ge₃N₄, SiO₂, NaNO₃Mg_(0.465)Ca_(0.79)Ba_(0.39)Eu_(0.03)Ce_(0.05)Si₅N_(7.5)O_(0.5) Mg₃N₂,Ca₃N₂, Ba₃N₂, CeN, Si₃N₄, SiO₂, EuNCa_(0.81)Ba_(0.855)Eu_(0.01)Ce_(0.05)Si₅N_(7.5)O_(0.5) Ca₃N₂, Ba₃N₂,CeN, Si₃N₄, SiO₂, EuNSr_(0.59)Ca_(0.4)Mg_(0.93)Ce_(0.04)Na_(0.04)Si_(4.8)N_(7.67)O_(0.5)C_(0.2)Ca₃N₂, Mg₃N₂, Sr₃N₂, CeN, Si₃N₄, SiO₂, NaNO₃, CSr_(0.59)Ca_(0.1)Mg_(0.83)Ce_(0.04)Na_(0.04)Si_(4.8)N_(7.67)O_(0.5)C_(0.2)Ca₃N₂, Mg₃N₂, Sr₃N₂, CeN, Si₃N₄, SiO₂, NaNO₃, CSr_(0.99)Mg_(0.93)Ce_(0.05)K_(0.05)Al_(0.5)Si_(4.5)N_(7.0)O_(1.0) Mg₃N₂,Sr₃N₂, AlN, CeN, Si₃N₄, SiO₂, KNO₃Sr_(0.99)Mg_(0.93)Ce_(0.05)K_(0.05)B_(0.2)Si_(4.8)N_(7.3)O_(0.7) Mg₃N₂,Sr₃N₂, AlN, CeN, Si₃N₄, SiO₂, KNO₃, B₂O₃Sr_(0.3)Mg_(0.25)Ce_(0.05)Na_(0.05)Si₅N_(5.3)O_(2.7) Mg₃N₂, Sr₃N₂, CeN,Si₃N₄, SiO₂, NaNO₃Sr_(0.1)Ba_(0.25)Ca_(0.1)Mg_(0.1)Ce_(0.05)Na_(0.05)Si₅N_(5.3)O_(2.7)Mg₃N₂, Sr₃N₂, Ca₃N₂, Ba₃N₂, CeN, Si₃N₄, SiO₂, NaNO₃Mg_(0.3)Ca_(0.62)Sr_(1.0)Ce_(0.04)Na_(0.04)Si₅N_(7.67)O_(0.5) Mg₃N₂,Ca₃N₂, Sr₃N₂, CeN, NaNO₃, Si₃N₄, SiO₂ Mg_(0.82)Ca_(0.2)Sr_(0.90)Ce_(0.04)Na_(0.04)Si₅N_(7.67)O_(0.5) Mg₃N₂, Ca₃N₂, Sr₃N₂, CeN,NaNO₃, Si₃N₄, SiO₂ Mg_(0.4)Ca_(0.4)Sr_(0.85)Ce_(0.05)Na_(0.05)Si₅N_(7.5)O_(0.5) Mg₃N₂, Ca₃N₂, Sr₃N₂, CeN,NaNO₃, Si₃N₄, SiO₂ Mg_(0.4)Ca_(0.4) Sr_(0.875)Ce_(0.05)Si₅N_(7.5)O_(0.5)Mg₃N₂, Ca₃N₂, Sr₃N₂, CeN, Si₃N₄, SiO₂ Mg_(0.2)Ca_(0.275)Ba_(1.2)Ce_(0.05)Si₅N_(7.5)O_(0.5) Mg₃N₂, Ca₃N₂, Ba₃N₂, CeN, Si₃N₄, SiO₂Ca_(0.5) Sr_(0.2) Ba_(1.2)Ce_(0.05)Na_(0.05)Si₅N_(7.67)O_(0.5) Ba₃N₂,Ca₃N₂, Sr₃N₂, CeN, NaNO₃, Si₃N₄, SiO₂

The corresponding fluorescence spectra show emission bands in the yellowwavelength region. The following emission maxima (peak wavelengths) maybe mentioned by way of example:

Ca_(0.5) Sr_(0.2)Ba_(1.2)Ce_(0.05)Na_(0.05)Si₅N_(7.67)O_(0.5): peakwavelength: 552 nm

Mg_(1.12)Ca_(0.4) Ba_(0.40)Ce_(0.04)Na_(0.04)Si₅N_(7.67)O_(0.5): peakwavelength 571 nm

Ca_(0.81)Ba_(0.855)Eu_(0.01) Ce_(0.05)Si₅N_(7.5)O_(0.5): peak wavelength595 nm

Example 1c (Sr,Ba)_(1.70)Ce_(0.10)Li_(0.10)Si₅N_(7.8)O_(0.2)

0.434 g of CeO₂ (2.52 mmol), 0.029 g of Li₃N (0.84 mmol), 3.500 g ofBa₃N₂ (7.95 mmol), 5.552 g of Si₃N₄(39.58 mmol), 0.376 g of SiO₂ (6.25mmol) and 2.313 g of Sr₃N₂(7.95 mmol) are weighed out together in aglove box and mixed in the hand mortar until a homogeneous mixture hasformed.

The mixture is transferred into a boron nitride boat and placed in thecentre of a tubular furnace on a molybdenum foil tray and calcined at1625° C. for 6 hours under a nitrogen/hydrogen atmosphere (60 l/min ofN₂+25 l/min of H₂).

Example 1d (Sr,Ba)_(1.70)Ce_(0.10)Li_(0.10)Si₅N_(7.8)O_(0.2)

1.721 g of CeO₂ (10 mmol), 0.116 g of Li₃N (3.333 mmol), 28.008 g ofBa₃N₂ (63.336 mmol), 22.660 g of Si₃N₄(158.300 mmol) and 1.502 g of SiO₂(25.000 mmol) are weighed out together in a glove box and mixed in thehand mortar until a homogeneous mixture has formed.

The mixture is transferred into a boron nitride boat and placed in thecentre of a tubular furnace on a molybdenum foil tray and calcined at1625° C. for 8 hours under a nitrogen/hydrogen atmosphere (60 l/min ofN₂+20 l/min of H₂).

20 percent by weight of strontium nitride are added to the resultantphosphor in a glove box and mixed until a homogeneous mixture hasformed. A further calcination is subsequently carried out, with theconditions identical to the first calcination step. In order to removeexcess nitride, the resultant phosphor is suspended in 1 molarhydrochloric acid for a further one hour, subsequently filtered off anddried.

Example 1e (Sr,Ba)_(1.82)Ce_(0.02)Li_(0.02) Eu_(0.04)Si₅N_(7.8)O_(0.2)

0.086 g of CeO₂ (0.50 mmol), 0.006 g of Li₃N (0.17 mmol), 0.352 g ofEu₂O₃ (1 mmol), 3.500 g of Ba₃N₂(7.95 mmol), 6.077 g of Si₃N₄(43.33mmol), 0.376 g of SiO₂ (6.25 mmol) and 2.313 g of Sr₃N₂(7.95 mmol) areweighed out together in a glove box and mixed in the hand mortar until ahomogeneous mixture has formed. The mixture is transferred into a boronnitride boat and placed in the centre of a tubular furnace on amolybdenum foil tray and calcined at 1625° C. for 6 hours under anitrogen/hydrogen atmosphere (50 l/min of N₂+20 l/min of H₂).

Example 2 Coating of the Phosphors Example 2a Coating of the PhosphorsAccording to the Invention with SiO₂

50 g of one of the phosphors according to the invention described aboveare suspended in 1 litre of ethanol in a 2 l reactor with ground-glasslid, heating mantle and reflux condenser. A solution of 17 g of ammoniawater (25% by weight of NH₃) in 70 ml of water and 100 ml of ethanol isadded. A solution of 48 g of tetraethyl orthosilicate (TEOS) in 48 g ofanhydrous ethanol is slowly added dropwise (about 1.5 ml/min) at 65° C.with stirring. When the addition is complete, the suspension is stirredfor a further 1.5 h, brought to room temperature and filtered. Theresidue is washed with ethanol and dried at 150° C. to 200° C.

Example 2B Coating of the Phosphors According to the Invention withAl₂O₃

50 g of one of the phosphors according to the invention described aboveare suspended in 950 g of ethanol in a glass reactor with heatingmantle. 600 g of an ethanolic solution of 98.7 g of AlCl₃*6H₂O per kg ofsolution are metered into the suspension over 3 h at 80° C. withstirring. During this addition, the pH is kept constant at 6.5 bymetered addition of sodium hydroxide solution. When the metered additionis complete, the mixture is stirred at 80° C. for a further 1 h, thencooled to room temperature, the phosphor is filtered off, washed withethanol and dried.

Example 2c Coating of the Phosphors According to the Invention with B₂O₃

50 g of one of the phosphors according to the invention described aboveare suspended in 1000 ml of water in a glass reactor with heatingmantle. The suspension is heated to 60° C., and 4.994 g of boric acidH₃BO₃ (80 mmol) are added with stirring. The suspension is cooled toroom temperature with stirring and subsequently stirred for 1 h. Thesuspension is then filtered off with suction and dried in a dryingcabinet. After drying, the material is calcined at 500° C. under anitrogen atmosphere.

Example 2d Coating of the Phosphors According to the Invention with BN

50 g of one of the phosphors according to the invention described aboveare suspended in 1000 ml of water in a glass reactor with heatingmantle. The suspension is heated to 60° C., and 4.994 g of boric acidH₃BO₃ (80 mmol) are added with stirring. The suspension is cooled toroom temperature with stirring and subsequently stirred for 1 h. Thesuspension is then filtered off with suction and dried in a dryingcabinet. After drying, the material is calcined at 1000° C. under anitrogen/ammonia atmosphere.

Example 2e Coating of the Phosphors According to the Invention with ZrO₂

50 g of one of the phosphors according to the invention described aboveare suspended in 1000 ml of water in a glass reactor with heatingmantle. The suspension is heated to 60° C. and adjusted to pH 3.0. 10 gof a 30 percent by weight ZrOCl₂ solution are subsequently metered inslowly with stirring. When the metered addition is complete, the mixtureis stirred for a further 1 h, subsequently filtered off with suction andwashed with DI water. After drying, the material is calcined at 600° C.under a nitrogen atmosphere.

Example 2f Coating of the Phosphors According to the Invention with MgO

50 g of one of the phosphors according to the invention described aboveare suspended in 1000 ml of water in a glass reactor with heatingmantle. The suspension is held at a temperature of 25° C., and 19.750 gof ammonium hydrogencarbonate (250 mmol) are added. 100 ml of a 15percent by weight magnesium chloride solution are added slowly. When themetered addition is complete, the mixture is stirred for a further 1 h,subsequently filtered off with suction and washed with DI water. Afterdrying, the material is calcined at 1000° C. under a nitrogen/hydrogenatmosphere.

Example 3 LED Application of the Phosphors

Various concentrations of the phosphors prepared in accordance withExample 1 or the phosphors coated in Example 2 are prepared in siliconeresin OE 6550 from Dow Corning by mixing 5 ml of components A and 5 mlof components B of the silicone with identical amounts of the phosphor,so that the following silicone/phosphor mixing ratios are present aftercombination of the two dispersions A and B by homogenisation using aSpeedmixer:

5% by weight of phosphor,

10% by weight of phosphor,

15% by weight of phosphor and

30% by weight of phosphor.

These mixtures are each transferred into an Essemtek dispenser andintroduced into empty LED-3528 packages from Mimaki Electronics. Afterthe silicone has cured at 150° C. for 1 h, the light properties of theLEDs are characterised with the aid of a set-up consisting of componentsfrom Instrument Systems: CAS 140 spectrometer and ISP 250 integrationsphere. For the measurement, the LEDs are contacted with a currentstrength of 20 mA at room temperature using an adjustable current sourcefrom Keithley. The luminance (in lumens of the converted LED/mW opticaloutput of the blue LED chip) against colour point CIE x of the convertedLED is plotted as a function of the phosphor use concentration in thesilicone (5, 10, 15 and 30% by weight).

The lumen equivalent is a lighting quantity, familiar to the personskilled in the art, with the unit lm/W which describes the magnitude ofthe photometric luminous flux in lumens of a light source at a certainradiometric radiation power with the unit watt. The higher the lumenequivalent, the more efficient a light source.

The lumen is a photometric lighting quantity, familiar to the personskilled in the art, which describes the luminous flux of a light source,which is a measure of the total visible radiation emitted by a radiationsource. The greater the luminous flux, the brighter the light sourceappears to the observer.

CIE x and CIE y stand for the coordinates in the standard CIE colourchart (here standard observer 1931), familiar to the person skilled inthe art, by means of which the colour of a light source is described.

All the quantities mentioned above are calculated from emission spectraof the light source by methods familiar to the person skilled in theart.

DESCRIPTION OF THE FIGURES

FIG. 1: Powder X-ray diffraction pattern of Example 1, measured on aStadiP 611 KL transmission powder X-ray diffractometer from Stoe & Cie.GmbH, Cu-Kα1 radiation, germanium [111] focusing primary raymonochromator, linear PSD detector.

FIG. 2: Fluorescence spectrum of the product from Example 1, recordedusing an Edinburgh Instruments FS920 spectrometer at an excitationwavelength of 450 nm (peak wavelength: 560 nm). In the fluorescencemeasurement, the excitation monochromator is adjusted to the excitationwavelength, and the detector monochromator arranged after the sample isscanned between 467 and 850 nm in 1 nm steps, with the light intensitypassing through the detector monochromator being measured.

FIG. 3: Excitation spectrum of the product from Example 1, recordedusing an Edinburgh Instruments FS920 spectrometer. In the excitationmeasurement, the excitation monochromator is scanned between 250 nm and500 nm in 1 nm steps, while the fluorescent light from the sample isdetected constantly at a wavelength of 560 nm.

FIG. 4: Fluorescence spectrum of the product Mg_(0.79)Ca_(0.39)Ba_(0.465)Eu_(0.03)Ce_(0.05)Ce_(0.05)Si₅N_(7.5)O_(0.5) (from Example 1b)—recorded using an Edinburgh Instruments FS920 spectrometer at anexcitation wavelength of 450 nm. In the fluorescence measurement, theexcitation monochromator is adjusted to the excitation wavelength, andthe detector monochromator arranged after the sample is scanned between475 and 850 nm in 1 nm steps.

1. Compound containing an anionic skeleton structure, dopants andcations, where a. the anionic skeleton structure is characterised bycoordination tetrahedra GL₄-, where G stands for silicon, which may bepartly replaced by C, Ge, B, Al or In, and L stands for N and O, withthe proviso that N makes up at least 60 atom-% of L, b. the cations areselected from the alkaline-earth metals, with the proviso that strontiumand barium together make up less than 75 atom-% of the cations, c. thedopant present is trivalent cerium or a mixture of trivalent cerium anddivalent europium, d. the charge compensation of the cerium doping takesplace i) via corresponding replacement of alkaline-earth metal cationsby alkali-metal cations and/or ii) via a corresponding increase in thenitrogen content and/or iii) via a corresponding reduction in thealkaline-earth metal cations.
 2. Compound according to claim 1,characterised in that the alkaline-earth metal cations are strontium,magnesium, calcium and/or barium, where calcium and magnesium togethermake up 25 atom-% or more of the alkaline-earth metal cations and in thesame or a further alternative embodiment calcium and magnesium togethermake up from 30 atom-% to 80 atom-% of the alkaline-earth metal cations.3. Compound according to claim 1, characterised in that G stands formore than 80 atom-% of silicon or G stands for more than 90 atom-% ofsilicon.
 4. Compound according to claim 1, characterised in that siliconhas been partly replaced by C or Ge.
 5. Compound according to claim 1,characterised in that G is formed by silicon.
 6. Compound according toclaim 1, characterised in that it is a compound of the formula Ia,A_(2-0.5y-x+1.5z)M_(0.5x)Ce_(0.5x)G₅N_(8-y+z)O_(y)  (Ia) where A standsfor one or more elements selected from Ca, Sr, Ba, Mg, M stands for oneor more elements selected from Li, Na, K, G stands for Si, which may bepartly replaced by C, Ge, B, Al or In, x stands for a value from therange from 0.005 to 1 and y stands for a value from the range from 0.01to 3 and z stands for a value from the range from 0 to
 3. 7. Compoundaccording to claim 1, characterised in that it is a compound of theformula Ib,A_(2-0.5y-0.75x+1.5z)Ce_(0.5x)G₅N_(8-y+z)O_(y)  (Ib) where A stands forone or more elements selected from Ca, Sr, Ba, Mg, M stands for one ormore elements selected from Li, Na, K, G stands for Si, which may bepartly replaced by C, Ge, B, Al or In, x stands for a value from therange from 0.005 to 1 and y stands for a value from the range from 0.01to 3 and z stands for a value from the range from 0 to
 3. 8. Compoundaccording to claim 1, characterised in that the phosphor is a compoundof the formula Ic,A_(2-0.5y+1.5z)Ce_(0.5x)G₅N_(8+0.5x-y+z)O_(y)  (Ic) where A stands forone or more elements selected from Ca, Sr, Ba, Mg, M stands for one ormore elements selected from Li, Na, K, G stands for Si, which may bepartly replaced by C, Ge, B, Al or In, x stands for a value from therange from 0.005 to 1 and y stands for a value from the range from 0.01to 3 and z stands for a value from the range from 0 to
 3. 9. Compoundaccording to claim 6, characterised in that x stands for a value fromthe range from 0.01 to 0.8, alternatively from the range 0.02 to 0.7 andfurthermore alternatively from the range 0.05 to 0.6.
 10. Compoundaccording to claim 6, characterised in that y stands for a value fromthe range from 0.1 to 2.5, preferably from the range 0.2 to 2 andespecially preferably from the range 0.22 to 1.8.
 11. Compound accordingto claim 1, characterised in that europium is present in the dopant, andthe cations contain a proportion of barium.
 12. Compound according toclaim 1, characterised in that the compound is in the form of a mixturewith a silicon- and oxygen-containing compound.
 13. Process for thepreparation of a compound according to claim 1, characterised in that,in a step a), suitable starting materials selected from binary nitrides,halides and oxides or corresponding reactive forms thereto are mixed,and, in a step b), the mixture is thermally treated under non-oxidisingconditions.
 14. (canceled)
 15. Light source having at least one primarylight source, characterised in that the light source comprises at leastone compound according to claim
 1. 16. Light source according to claim15, characterised in that the light source comprises a red-emittingphosphor.
 17. Lighting unit, in particular for the backlighting ofdisplay devices, characterised in that it comprises at least one lightsource according to claim
 15. 18. Display device, in particularliquid-crystal display device (LC display), with backlighting,characterised in that it comprises at least one lighting unit accordingto claim
 17. 19. A method for the partial or complete conversion of theblue or near-UV emission from a primary light source, preferably aluminescent diode or a laser, into light in the yellow spectral region,comprising achieving said conversion by a compound according to claim 1.